As a cost of gold has recently increased, efforts to reduce an amount of gold included in electronic components have been made in the electronics industry. However, for the surface treatment of a printed circuit board and a wire connected to a semiconductor chip, gold is being mainly used. Accordingly, the electronic components industry has been making efforts to replace a gold wire with a copper wire, and researches on the bonding between a copper wire and a chip have been conducted by many companies in each country.
FIG. 1 is a view for explaining a surface treatment structure of a printed circuit board according to a conventional art.
Referring to FIG. 1, upon the conventional surface treatment of the printed circuit board, a nickel-gold plated layer or a nickel-palladium-gold plated layer is generally used. At this time, the plated layers are layers which are designed to be suitable for a gold wire. Thus, a soft gold plated layer is finally formed so as to be connected to the gold wire.
However, when copper wire bonding is applied to the plated layers having the above structure, the bonding between the copper wire and the plated layers is made, but due to the property of soft gold, it was problematic that a bonding yield of the hard copper wire is low, and a bonding ability is reduced.
A surface treatment structure including a silver plated layer which will be hereinafter applied also has the same problem as the above. That is, like gold, silver also has a soft property, so upon the bonding of the copper wire and the silver plated layer, the plated layer does not sufficiently support the copper wire, thereby lowering a bonding ability.